The decision was spurred by the movement of options trading to ICE's computerized trading system. This is significant, and is likely the beginning of the end of floor trading. Options have been the last major bastion of open outcry. Many options trades involve more complicated multi-leg strategies (including spreads of various sorts) that are more difficult to computerize than simple outright futures trades, or simple futures strategies like calendar spreads, but which can be done efficiently on the floor; locals on the floors quote many of the common spreads. If options can be done on the screens, there's nothing really left for the floor to do.

Thus, we are witnessing the culmination of a process that began about 20 years ago. I first did some research on electronic trading in the early-1990s, and remember the disdain with which the futures and options communities looked on computerized markets. In 1995, I wrote a study comparing the electronic DTB and the open outcry LIFFE market which found that the former was as liquid, or more liquid than the latter. This study was met with much derision by LIFFE, and by most people in Chicago. The derision of electronic trading died down substantially in 1998, when volume in the Bund futures market tipped completely to DTB's successor (Eurex), and LIFFE suffered a near death experience.

The floor held out in the U.S. for sometime longer, but by the early-2000s the writing was on the wall here as well. By the mid-2000s, options trading was keeping the floors going. But that's no longer true of ICE, and it is likely a matter of time before it is no longer true on CME/CBT (NASDAQ:CME) or NYMEX.